Push button 4WD transfer case won't shift to 4HI/4LO

Discussion in 'Transfer Cases' started by GT80, Sep 6, 2019.

  1. GT80

    GT80 Newbie

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    First post here. I've scoured this forum for a solution to my problem but can't find any threads with this particular issue. Truck is a 98 model with push button 4wd. NP 243 C t-case.

    When I try to engage 4HI or 4LO, I hear relays clicking and I sometimes get a clunk from the transfer case, the lights flash a couple times, but then it reverts back to 2HI.

    Here's what I have done so far. I checked the TCCM for codes and only get DTC 1. I assume that's from all my battery disconnecting and fuse removal. (edit - I cycled the ignition switch 5 times and got rid of this code, so now there are no trouble codes.)

    I replaced the switch on the top of the transfer case since it was a cheap and easy part. That didn't help. Here's where things get strange. I then replaced the encoder motor on the t-case. When I got the new motor, the paperwork said that it was shipped in the 2HI position and that if my transfer case wasn't in 2HI I would have to manually shift it to get the tang to align. Well, this motor was in the 4HI position, and even had a plastic keeper "holding" it there (although I can't see how it could move on its own). So I shifted the t-case to 4HI with a crescent wrench and installed the motor. When I turned the key on, the light on the 4HI dash switch was lit and I thought great, I should be good to go. Well, then the t-case shifted beautifully between 4HI and 4LO, the actuator engaged the front differential and everything worked great EXCEPT now I couldn't shift out of 4WD to 2HI. Another issue was when in 4HI, when I shifted to reverse, I got a grinding noise from the t-case. What I found when I pulled this motor back off was that when in 4HI it had the tang on the t-case turned a few degrees toward 4LO so I assume that's why it was grinding. Also, the plastic keeper it was shipped with wouldn't align anymore.

    So, I got a reman'd Delco encoder motor. This one was in fact shipped in the 2HI position. I installed it and still had the original issue. Won't shift out of 2HI. The last thing I did was try a new TCCM and that didn't help. Same issue.

    Any more ideas? I've basically tested/replaced every electronic component I know of in the 4WD system except the dash switches. I assume the switches are OK because I hear relays clicking and lights are flashing. Is this a bad assumption?
     
    Last edited: Sep 6, 2019
  2. b454rat

    b454rat I'm Awesome

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    Kinda sounds like the t-case itself is sticking. Maybe find a trail or somewhere to test the 4wd out. Drive around in hi, then go back to 2wd, then low. Might just need to get motivated lol.
     
  3. GT80

    GT80 Newbie

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    At this point, the only way I can get it into 4wd is to remove the encoder motor and turn the tang with a crescent wrench.
     
  4. b454rat

    b454rat I'm Awesome

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    I had one that the motor was bad. I put a good used one in, but seemed to stick at first. I would drive it around the yard in 4 hi, go out in the road in 2 hi, then back in yard in 4 lo. Other than that, I'm out lol.
     
  5. NickG80

    NickG80 Newbie

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    Remove the tail shaft housing the snap ring is probably broken.
     
  6. GT80

    GT80 Newbie

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    So this can cause my shifting issue?
     
  7. Supercharged111

    Supercharged111 I'm Awesome

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    If that is the case, there is an upgrade that eliminate the clip. Can you hear the actuator in the front diff doing it thing too? That's what took a dump when my truck refused to go into 4wd.
     
  8. GT80

    GT80 Newbie

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    There's no problem with the front actuator. The issue is in shifting the transfer case to/from 4wd, which I can do manually no problem with a crescent wrench, but the encoder motor won't do it.
     
  9. GT80

    GT80 Newbie

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    No one has had this particular issue? I'm at my wit's end!! I so wish my truck was manual. Push button is nice until it shits the bed.
     

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